Fluorescent entity, dyeing composition containing at least one fluorescent entity comprising at least one heterocycle, with at least one internal cationic charge, and method for lightening keratin materials using said at least one fluorescent entity

ABSTRACT

The invention relates to a dyeing composition containing a thiol/disulphide fluorescent colorant comprising a heterocycle, and to a method for colouring keratin materials, especially keratin fibres, particularly human keratin fibres such as hair, with a lightening effect, using said composition. The invention also relates to novel thiol/disulphide fluorescent colorants and the uses thereof for lightening keratin materials. Said composition produces a lightening effect which is especially tenacious and visible on dark keratin fibres.

The invention relates to the dyeing of keratin materials using thiol ordisulphide fluorescent dyes comprising a heterocycle.

It is known practice to dye keratin fibres, in particular human keratinfibres, by direct dyeing. The process conventionally used in directdyeing comprises applying to the keratin fibres direct dyes which arecoloured or colouring molecules having an affinity for the fibres,allowing them to diffuse and then rinsing the fibres.

The direct dyes which are conventionally used are, for example, dyes ofthe nitrobenzene type, anthroquinone dyes, nitropyrridine dyes, or dyesof the azo, xanthene, acridine, azine or triarylmethane type.

The colourings which result from the use of direct dyes are temporary orsemipermanent colourings since the nature of the interactions which bindthe direct dyes to the keratin fibre and their disorption from thesurface and/or from the core of the fibre are responsible for their weakdyeing power and for their poor resistance to washing operations or toperspiration.

Moreover, the colouring of keratin fibres using conventional direct dyesdoes not make it possible to significantly lighten keratin fibres.

The lightening of the colour of keratin fibres, more particularly darkkeratin fibres to lighter shades, by optionally modifying the shadethereof, constitutes an important demand.

Conventionally, in order to obtain a lighter colouring, a chemicalbleaching process is used. This process comprises treating the keratinmaterials, such as keratin fibres, in particular the hair, with a strongoxidizing system, generally composed of hydrogen peroxide, possibly incombination with persalts, generally in an alkaline medium.

This bleaching system has the drawback of damaging keratin materials, inparticular keratin fibres, especially human keratin fibres such as thehair, and of detrimentally affecting their cosmetic properties. Thefibres in fact have a tendency to become rough, more difficult todisentangle and more brittle. Finally, the lightening or bleaching ofkeratin fibres using oxidizing agents is incompatible with thetreatments for modifying the shape of said fibres, particularly in hairstraightening treatments.

Another lightening technique comprises applying fluorescent direct dyesto dark hair. This technique, described in particular in documents FR 2830 189 and WO 2004/091473, makes it possible to retain the quality ofthe keratin fibre during the treatment, but the fluorescent dyes used donot exhibit satisfactory resistance to shampooing operations.

In order to increase the fastness of direct dyes, it is known practiceto fix direct dyes by covalent bonding to the hair. For example, it isknown practice to react dyes comprising reactive groups with the verynumerous cystine or cysteine residues in keratin fibres; see, forexample, Journal of the Society of Dyers and Colourists, Guise andStapleton, 91, 259-264 (1975); Journal of Cosmetic Chemistry, 42, 1-17(1991); CA 2024509.

Furthermore, it is known practice to protect the thiol function(s)contained in a molecule to be grafted to the hair before applying themto said hair, WO 99/51194. However, this application does not mentionthe use of fluorescent dyes for dyeing or lightening hair.

Other disulphide dyes known for dyeing keratin fibres are disulphidederivatives of aminothiophenol derivatives. Such dyes are described, forexample, in patent FR 1156407. These dyes can be used under relativelymild conditions, in the presence of a slightly reducing medium or aftera reducing pre-treatment of the hair. However, these dyes can bringabout colour changes during application.

Finally, document WO 2005/097051 describes azaimidazolium disulphidedyes for the direct dyeing of keratin fibres.

The aim of the present invention is to provide new systems for dyeingkeratin materials, in particular human keratin fibres, especially thehair, which do not have the drawbacks of the existing bleachingprocesses. In particular, one of the aims of the present invention is toprovide direct dyeing systems for obtaining lightening effects,especially on naturally or artificially dark keratin fibres, which areresistant to successive shampooing operations, which do not damage thekeratin fibres and which do not detrimentally affect their cosmeticproperties.

This aim is achieved with the present invention, a subject of which is aprocess for dyeing keratin materials, in particular keratin fibres,especially human keratin fibres such as the hair, more particularly darkhair, comprising applying, to the keratin materials, a dye compositioncomprising, in a cosmetically suitable medium, at least one fluorescentdye, chosen from the dyes of formulae (I) and (II) below:

the organic or mineral acid salts, optical isomers and geometricalisomers thereof, and the solvates such as hydrates; in which formulae(I) and (II):

-   -   which may be identical or different, represent a saturated or        unsaturated heterocyclic group; in particular a monocyclic        group, comprising from 5 to 7 members and containing 1 or two of        heteroatoms chosen from nitrogen, oxygen or sulphur atoms, in        particular the heteroatom is a nitrogen atom; in particular, the        heterocycle is chosen from pyrazolyl, pyrrolidinyl, piperazinyl,        homopiperazinyl, piperidinyl, morpholinyl and imidazolyl;    -   R_(g), R′_(g), R″_(g), R′″_(g), R_(h), R′_(h), R″_(h) and        R′″_(h), which may be identical or different, represent a        hydrogen or halogen atom, an amino, (di) (C₁-C₄)alkylamino,        cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄        alkoxy, C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,        (C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino,        carbamoyl or (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl        radical, or a (C₁-C₁₆)alkyl radical optionally substituted with        a group chosen from (C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl,        amino and (di) (C₁-C₄)alkylamino, or else the two alkyl radicals        borne by the nitrogen atom of the amino group form a heterocycle        comprising from 5 to 7 members and optionally comprising another        heteroatom identical to or different from that of the nitrogen        atom; in particular, R_(g), R′_(g), R″_(g), R′″_(g), R_(h),        R′_(h), R″_(h) and R′″_(h) represent a hydrogen atom or a        (C₁-C₄)alkyl group;    -   R_(i), R′_(i), R″_(i) and R′″_(i), which may be identical or        different, represent a hydrogen atom or a (C₁-C₄) alkyl group;        in particular, R_(i), R′_(i), R″_(i) and R′″_(i) represent a        hydrogen atom;    -   R₁, R′₁, R₂, R′₂, R₃, R′₃, R₄ and R′₄, which may be identical or        different, represent a hydrogen atom or a (C₁-C₄)alkyl,        (C₁-C₄)alkoxy, hydroxyl, cyano, carboxyl, amino,        (C₁-C₄)alkylamino or (C₁-C₄) dialkylamino group, it being        possible for said alkyl radicals to form, with the nitrogen atom        which bears them, a heterocycle comprising from 5 to 7 members,        optionally comprising another heteroatom which may or may not be        different from nitrogen; in particular, R₁, R′₁, R₂, R′₂, R₃,        R′₃/R₄ and R′₄ are hydrogen atoms or an amino group; in        particular, R₁, R′₁, R₂, R′₂, R₃, R′₃, R₄ and R′₄ represent a        hydrogen atom;    -   T_(a) and T_(b), which may be identical or different, represent:    -   i) either a σ covalent bond;    -   ii) or one or more radicals or combinations thereof chosen from        —SO₂—, —O—, —S—, —N(R)—, —N⁺(R)(R^(o))— and —C(O)—, with R and        R^(o), which may be identical or different, representing a        hydrogen atom, a C₁-C₄ alkyl radical, a C₁-C₄ hydroxyalkyl        radical or an aryl(C₁-C₄)alkyl; in particular, T_(a) is        identical to T_(b) and they represent a σ covalent bond or a        group chosen from —N(R)—, —C(O)—, —C(O)—N(R)—, —N(R)—C(O)—,        —C(O)—N(R)—C(O)—, —O—C(O)—, —C(O)—O— and —N⁺(R)(R^(o))—, with R        and R^(o), which may be identical or different, representing a        hydrogen atom or a (C₁-C₄) alkyl group; in particular, T_(a) and        T_(b) represent a σ bond; iii) or a preferably monocyclic,        cationic or noncationic heterocycloalkyl or heteroaryl        containing especially two heteroatoms, in particular two        nitrogen atoms, and comprising in particular from 5 to 7        members, such as imidazolium, piperazyl, piperazinium,        homopiperazyl or homopiperazinium, optionally substituted with a        (C₁-C₄) alkyl group such as methyl;    -   m, m′, n and n′, which may be identical or different, represent        an integer between 0 and 6 inclusive, with m+n and m′+n′, which        may be identical or different, representing an integer between 1        and 10 inclusive; in particular, the sum m+n=m′+n′=an integer        between 2 and 4 inclusive; preferably, m+n=m′+n′=2;    -   M′ represents an anionic counterion; and    -   Y represents: i) a hydrogen atom; ii) an alkali metal; iii) an        alkaline earth metal; iv) an ammonium group:        N⁺R^(α)R^(β)R^(γ)R^(δ) or a phosphonium group:        P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(α), R^(β), R^(γ) and R^(δ), which        may be identical or different, representing a hydrogen atom or a        (C₁-C₄)alkyl group; or v) a thiol-function-protecting group;        it being understood that:    -   when the compound of formula (I) or (II) contains other cationic        parts, it is associated with one or more anionic counterions        allowing formula (I) or (II) to achieve electroneutrality.

Another subject of the invention is a dye composition comprising, in asuitable cosmetic medium, at least one fluorescent dye of formula (I) or(II) as defined above, and optionally a reducing agent.

A subject of the invention is also novel fluorescent dyes of formula (I)or (II) as defined above.

The dyeing process according to the invention makes it possible tovisibly colour dark keratin materials, in particular dark human keratinfibres, especially dark hair.

Furthermore, the process of the invention makes it possible to obtaincolouring of keratin materials, in particular human keratin fibres,especially the hair, without damaging said material, which is persistentwith respect to shampooing operations, common attacks (sunlight,perspiration), and other hair treatments. The process of the inventionalso makes it possible to obtain lightening of keratin materials such askeratin fibres, in particular dark keratin fibres, and more particulardark hair.

For the purpose of the invention, the term “dark keratin material” isintended to mean that which exhibits a lightness of L* measured in theC.I.E. L*a*b* system of less than or equal to 45, and preferably lessthan or equal to 40, given that, moreover, L*=0 is equivalent to blackand L*=100 is equivalent to white.

For the purpose of the invention, the expression “naturally orartificially dark hair” is intended to mean hair whose tone height isless than or equal to 6 (dark blonde) and preferably less than or equalto 4 (chestnut-brown).

The lightening of the hair is evaluated by the variation in “toneheight” before or after application of the compound of formula (I) or(II).

The notion of “tone” is based on the classification of the naturalshades, one tone separating each shade from the shade immediatelyfollowing or preceding it. This definition and the classification of thenatural shades are well known to hair styling professionals and arepublished in the book “Science des traitement capillaires” [Hairtreatment sciences], by Charles Zviak 1988, published by Masson, pp. 215and 278.

The tone heights range from 1 (black) to 10 (very light blonde), oneunit corresponding to one tone; the higher the figure, the lighter theshade.

An artificially coloured hair is a hair whose colour has been modifiedby a dyeing treatment, for example dyeing with direct dyes or oxidationdyes.

Preferably, the composition should, after application to hair, forexample chestnut-brown hair, lead to the results below.

-   -   Interest is focussed on the reflectance performance levels of        the hair when it is irradiated with visible light in the        wavelength range from 400 to 700 nanometres.    -   The curves of reflectance as a function of wavelength, of hair        treated with the composition of the invention and of untreated        hair, are then compared.    -   The curve corresponding to the treated hair should show a        reflectance in the wavelength range of from 500 to 700        nanometres which is higher than the curve corresponding to the        untreated hair.    -   This means that, in the wavelength range from 540 to 700        nanometres, there is at least one range where the reflectance        curve corresponding to the treated hair is higher than the        reflectance curve corresponding to the untreated hair. The term        “higher” is intended to mean a difference of at least 0.05% in        reflectance, preferably of at least 0.1%. All the same, there        may be, in the wavelength range of from 540 to 700 nanometres,        at least one range where the reflectance curve corresponding to        the treated hair is superimposable or lower than the reflectance        curve corresponding to the untreated hair.

Preferably, the wavelength where the difference is at a maximum betweenthe reflectance curve of the treated hair and that of the untreated hairis within the wavelength range of from 500 to 650 nanometres, andpreferably within the wavelength range of from 550 to 620 nanometres.

For the purpose of the present invention, and unless otherwiseindicated:

-   -   the “aryl” or “heteroaryl” radicals or the aryl or heteroaryl        part of a radical may be substituted with at least one        substituent borne by a carbon atom, chosen from:        -   a C₁-C₁₆/preferably C₁-C₈, alkyl radical optionally            substituted with one or more radicals chosen from the            radicals: hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy,            acylamino and amino substituted with two C₁-C₄ alkyl            radicals, which may be identical or different, optionally            bearing at least one hydroxyl group, or the two radicals            possibly forming, with the nitrogen atom to which they are            attached, a heterocycle comprising from 5 to 7 members,            preferably 5 or 6 members, which is saturated or            unsaturated, which is optionally substituted, and which            optionally comprises another heteroatom which may be            identical or different from the nitrogen;        -   a halogen atom such as chlorine, fluorine or bromine;        -   a hydroxyl group;        -   a C₁-C₂ alkoxy radical;        -   C₁-C₂ alkylthio radical;        -   a C₂-C₄ (poly)hydroxyalkoxy radical;        -   an amino radical;        -   a 5- or 6-membered heterocycloalkyl radical;        -   an optionally cationic 5- or 6-membered heteroaryl radical,            preferably imidazolium, optionally substituted with a C₁-C₄            alkyl radical, preferably methyl;        -   an amino radical substituted with one or two C₁-C₆ alkyl            radicals, which may be identical or different, optionally            bearing at least:            -   i) one hydroxyl group,            -   ii) one amino group optionally substituted with one or                two optionally substituted C₁-C₃ alkyl radicals, said                alkyl radicals possibly forming, with the nitrogen atom                to which they are attached, a heterocycle comprising                from 5 to 7 members, which is saturated or unsaturated,                which is optionally substituted, and which optionally                comprises at least one heteroatom which may or may not                be different from nitrogen,        -   —NR—COR′ in which the R radical is a hydrogen atom or a            C₁-C₄ alkyl radical optionally bearing at least one hydroxyl            group, and the R′ radical is a a C₁-C₂ alkyl radical;        -   (R)₂N—CO— in which the R radicals, which may or may not be            identical, represent a hydrogen atom, or a C₁-C₄ alkyl            radical optionally bearing at least one hydroxyl group;        -   R′SO₂—NR— in which the R radical represents a hydrogen atom            or a C₁-C₄ alkyl radical optionally bearing at least one            hydroxyl group, and the R′ radical represents a C₁-C₄ alkyl            radical or a phenyl radical;        -   (R)₂N—SO₂— in which the R radicals, which may or may not be            identical, represent a hydrogen atom or a C₁-C₄ alkyl            radical optionally bearing at least one hydroxyl group,        -   a carboxylic radical in acid or salified form (preferably            with an alkali metal or an ammonium, which is substituted or            unsubstituted);        -   a cyano group;        -   a polyhaloalkyl group containing from 1 to 6 carbon atoms            and from 1 to 6 halogen atoms, which may be identical or            different; the polyhaloalkyl group is, for example,            trifluoromethyl;    -   the cyclic or heterocyclic part of a nonaromatic radical may be        substituted with at least one substituent borne by a carbon        atom, chosen from the groups:        -   hydroxyl;        -   C₁-C₄ alkoxy;        -   C₂-C₄ (poly)hydroxyalkoxy;        -   a C₁-C₂ alkylthio radical;        -   RCO—NR′— in which the R′ radical is a hydrogen atom or a            C₁-C₄ alkyl radical optionally bearing at least one hydroxyl            group, and the R radical is a C₁-C₂ alkyl radical or an            amino radical substituted with two C₁-C₄ alkyl groups, which            may be identical or different, optionally bearing at least            one hydroxyl group;        -   RCO—O— in which the R radical is a C₁-C₄ alkyl radical or an            amino radical substituted with one or two C₁-C₄ alkyl            groups, which may be identical or different, optionally            bearing at least one hydroxyl group, said alkyl radicals            possibly forming, with the nitrogen atom to which they are            attached, a heterocycle comprising from 5 to 7 members,            which is saturated or unsaturated, which is optionally            substituted, and which optionally comprises at least one            other heteroatom which may or may not be different from            nitrogen;        -   RO—CO— in which the R radical is a C₁-C₄ alkyl radical            optionally bearing at least one hydroxyl group;    -   a cyclic or heterocyclic radical or a nonaromatic part of an        aryl or heteroaryl radical may also be substituted with one or        more oxo or thioxo groups;    -   an “aryl” radical represents a condensed or noncondensed,        monocyclic or polycyclic group containing from 6 to 22 carbon        atoms, and at least one ring of which is aromatic; preferably,        the aryl radical is a phenyl, biphenyl, naphthyl, indenyl,        anthracenyl or tetrahydronaphthyl;    -   a “diarylalkyl” radical represents a group comprising, on the        same carbon atom of an alkyl group, two aryl groups, which may        be identical or different, such as diphenylmethyl or        1,1-diphenylethyl;    -   a “heteroaryl radical” represents an optionally cationic,        condensed or noncondensed, monocyclic or polycyclic group        comprising from 5 to 22 members and from 1 to 6 heteroatoms        chosen from a nitrogen, oxygen, sulphur and selenium atom, and        at least one ring of which is aromatic; preferably, a heteroaryl        radical is chosen from acridinyl, benzimidazolyl,        benzobistriazolyl, benzopyrazolyl, benzopyridazinyl,        benzoquinolyl, benzothiazolyl, benzotriazolyl, benzoxazolyl,        pyridinyl, tetrazolyl, dihydrothiazolyl, imidazopyridinyl,        imidazolyl, indolyl, isoquinolyl, naphthoimidazolyl,        naphthooxazolyl, naphthopyrazolyl, oxadiazolyl, oxazolyl,        oxazolopyridyl, phenazinyl, phenooxazolyl, pyrazinyl, pyrazolyl,        pyrilyl, pyrazoyltriazyl, pyridyl, pyridinoimidazolyl, pyrrolyl,        quinolyl, tetrazolyl, thiadiazolyl, thiazolyl,        thiazolopyridinyl, thiazoylimidazolyl, thiopyrylyl, triazolyl,        xanthylyl and its ammonium salt;    -   a “diheteroarylalkyl” radical represents a group comprising, on        the same carbon atom of an alkyl group, two heteroaryl groups,        which may be identical or different, such as difurylmethyl,        1,1-difurylethyl, dipyrrolylmethyl or dithienylmethyl;    -   a “cyclic radical” is a condensed or noncondensed, monocyclic or        polycyclic, nonaromatic cycloalkyl radical containing from 5 to        22 carbon atoms, possibly comprising one or more unsaturations;        in particular, the cyclic radical is a cyclohexyl;    -   a “sterically hindered cyclic” radical is a substituted or        unsubstituted, aromatic or nonaromatic, cyclic radical hindered        by steric effect or constraint, comprising from 6 to 14 members,        which may be bridged; by way of sterically hindered radicals,        mention may be made of bicyclo[1.1.0]butane, mesityls such as        1,3,5-trimethylphenyl, 1,3,5-tri-tert-butylphenyl,        1,3,5-isobutylphenyl, 1,3,5-trimethylsilylphenyl and adamantyl;    -   a “heterocyclic radical or heterocycle” is a condensed or        noncondensed, monocyclic or polycyclic, nonaromatic radical        containing from 5 to 22 members, comprising from 1 to 6        heteroatoms chosen from nitrogen, oxygen, sulphur and selenium;    -   an “alkyl radical” is a linear or branched, C₁-C₁₆, preferably        C₁-C₈, hydrocarbon-based radical;    -   the expression “optionally substituted” assigned to the alkyl        radical implies that said alkyl radical may be substituted with        one or more radicals chosen from the radicals: i) hydroxyl; ii)        C₁-C₄ alkoxy; iii) acylamino; iv) amino optionally substituted        with one or two C₁-C₄ alkyl radicals, which may be identical or        different, said alkyl radicals possibly forming, with the        nitrogen atom which bears them, a heterocycle comprising from 5        to 7 members, optionally comprising another heteroatom which may        or may not be different from nitrogen; v) or a quaternary        ammonium group —N⁺R′R″R′″, M⁻ for which R′, R″, R′″, which may        be identical or different, represent a hydrogen atom or a C₁-C₄        alkyl group, or else —N⁺R′R″R′″ forms a heteroaryl such as        imidazolium optionally substituted with a C₁-C₄ alkyl group, and        M⁻ represents the counterion of the corresponding organic acid,        mineral acid or halide;    -   an “alkoxy radical” is an alkyloxy or alkyl-O— radical for which        the alkyl radical is a linear or branched, C₁-C₁₆, preferably        C₁-C₈, hydrocarbon-based radical;    -   an “alkylthio radical” is an alkyl-S— radical for which the        alkyl radical is a linear or branched, C₁-C₁₆, preferably C₁-C₈,        hydrocarbon-based radical; when the alkylthio group is        optionally substituted, this implies that the alkyl group is        optionally substituted as defined above;    -   the limits delimiting the extent of the range of values are        included in this range of values;    -   an “organic or mineral acid salt” is more particularly chosen        from a salt derived: i) from hydrochloric acid HCl; ii) from        hydrobromic acid HBr; iii) from sulphuric acid H₂SO₄; iv) from        alkylsulphonic acids: Alk-S(O)₂OH such as methylsulphonic acid        and ethylsulphonic acid; v) from arylsulphonic acids: Ar-(O)₂OH        such as from benzenesulphonic acid and from toluenesulphonic        acid; vi) from citric acid; vii) from succinic acid; viii) from        tartaric acid; ix) from lactic acid; x) from alkoxysulphinic        acids: Alk-O—S(O)OH such as from methoxysulphinic acid and from        ethoxysulphinic acid; xi) from aryloxysulphinic acids such as        from tolueneoxysulphinic acid and from phenoxysulphinic        acid; xii) from phosphoric acid H₃PO₄; xiii) from acetic acid        CH₃COOH; xiv) from triflic acid CF₃SO₃H and xv) from        tetrafluoroboric acid HBF₄;    -   an “anionic counterion” is an anion or an anionic group        associated with the cationic charge of the dye; more        particularly, the anionic counterion is chosen from: i) halides        such as chloride or bromide; ii) nitrates; iii) sulphonates,        among which are C₁-C₆ alkyl sulphonates: Alk-S(O)₂O⁻ such as        methyl sulphonate or mesylate and ethyl sulphonate; iv) aryl        sulphonates: Ar-S(O)₂O⁻ such as benzene sulphonate and        toluenesulphonate or tosylate; v) citrate; vi) succinate; vii)        tartrate; viii) lactate; ix) alkyl sulphates: Alk-O—S(O)O⁻ such        as methyl sulphate and ethyl sulphate; x) arylsulphates:        Ar-O—S(O)O⁻ such as benzenesulphate and toluenesulphate; xi)        alkoxysulphates: Alk-O—S(O)₂O⁻ such as methoxy sulphate and        ethoxy sulphate; xii) aryloxysulphates: Ar-O—S(O)₂O⁻; xiii)        phosphate; xiv) acetate; xv) triflate; and xvi) borates such as        tetrafluoroborate.

The fluorescent dyes of formula (I) or (II) are compounds capable ofabsorbing in the UV radiation or visible range at a wavelength λ_(abs)of between 250 and 800 nm and capable of re-emitting in the visiblerange at an emission wavelength λ_(em) of between 400 and 800 nm.

Preferably, the fluorescent compounds of the invention are dyes capableof absorbing in the visible range λ_(abs) of between 400 and 800 nm andof re-emitting in the visible range λ_(em) of between 400 and 800 nm.More preferably, the fluorescent dyes comprising a heterocyclic group offormula (I) or (II) are dyes capable of absorbing at a λ_(abs) ofbetween 420 nm and 550 nm and of re-emitting in the visible range at aλ_(em) of between 470 and 600 nm.

The fluorescent compounds of formula (II) which contain an SY functionwhich may be in the covalent form —S—Y or ionic form —S⁻Y⁺ depending onthe nature of Y and on the pH of the medium.

A specific embodiment relates to the thiol fluorescent dyes comprising agroup of formula (II) comprising an SY function where Y represents ahydrogen atom or an alkali metal. Advantageously, Y represents ahydrogen atom.

In accordance with another specific embodiment of the invention, in theabovementioned formula (II), Y is a protecting group known to thoseskilled in the art, for instance those described in the books“Protective Groups in Organic Synthesis”, T. W. Greene, John Willey &Sons publisher, NY, 1981, pp. 193-217; “Protecting Groups”, P.Kocienski, Thieme, 3rd ed., 2005, chap. 5.

Particularly when Y represents a thiol-function-protecting group, Y ischosen from the following radicals:

-   -   (C₁-C₄) alkylcarbonyl;    -   (C₁-C₄)alkylthiocarbonyl;    -   (C₁-C₄) alkoxycarbonyl;    -   (C₁-C₄)alkoxythiocarbonyl;    -   (C₁-C₄) alkylthiothiocarbonyl;    -   (di) (C₁-C₄)(alkyl)aminocarbonyl;    -   (di) (C₁-C₄)(alkyl)aminothiocarbonyl;    -   arylcarbonyl such as phenylcarbonyl;    -   aryloxycarbonyl;    -   aryl(C₁-C₄)alkoxycarbonyl;    -   (di) (C₁-C₄) (alkyl)aminocarbonyl such as        dimethyl-aminocarbonyl;    -   (C₁-C₄) (alkyl)arylaminocarbonyl;    -   carboxyl;    -   SO₃, M⁺ with M⁺ representing an alkali metal such as sodium or        potassium, or else M′ of formula (II) and M⁺ are absent;    -   optionally substituted aryl such as phenyl, dibenzosuberyl or        1,3,5-cycloheptatrienyl,    -   optionally substituted heteroaryl; including in particular the        cationic or noncationic heteroaryl comprising from 1 to 4        heteroatoms below:        -   i) monocyclic comprising 5, 6 or 7 members, such as furanyl            or furyl, pyrrolyl or pyrryl, thiophenyl or thienyl,            pyrazolyl, oxazolyl, oxazolium, isoxazolyl, isoxazolium,            thiazolyl, thiazolium, isothiazolyl, isothiazolium,            1,2,4-triazolyl, 1,2,4-triazolium, 1,2,3-triazolyl,            1,2,3-triazolium, 1,2,4-oxazolyl, 1,2,4-oxazolium,            1,2,4-thiadiazolyl, 1,2,4-thiadiazolium, pyrylium,            thiopyridyl, pyridinium, pyrimidinyl, pyrimidinium,            pyrazinyl, pyrazinium, pyridazinyl, pyridazinium, triazinyl,            triazinium, tetrazinyl, tetrazinium, azepine, azepinium,            oxazepinyl, oxazepinium, thiepinyl, thiepinium, imidazolyl,            imidazolium;        -   ii) bicyclic comprising 8 to 11 members, such as indolyl,            indolinium, benzoimidazolyl, benzoimidazolium, benzoxazolyl,            benzoxazolium, dihydrobenzoxazolinyl, benzothiazolyl,            benzothiazolium, pyridoimidazolyl, pyridoimidazolium,            thienocycloheptadienyl, these monocyclic or bicyclic groups            being optionally substituted with one or more groups such as            (C₁-C₄)alkyl, for instance methyl, or polyhalo(C₁-C₄)alkyl,            for instance trifluoromethyl; iii) or tricyclic ABC below:

in which the two rings A, C optionally comprise a heteroatom, and thering B is a 5-, 6- or 7-membered, particularly 6-membered ring andcontains at least one heteroatom, for instance piperidyl or pyranyl;

-   -   optionally cationic, optionally substituted heterocycloalkyl,        the heterocycloalkyl group represents in particular a saturated        or partially saturated, 5-, 6- or 7-membered monocyclic group        comprising from 1 to 4 heteroatoms chosen from oxygen, sulphur        and nitrogen, such as di/tetrahydrofuranyl,        di/tetrahydrothiophenyl, di/tetrahydropyrrolyl,        di/tetrahydropyranyl, di/tetra/hexahydrothiopyranyl,        dihydropyridyl, piperazinyl, piperidinyl,        tetramethylpiperidinyl, morpholinyl, di/tetra/hexahydroazepinyl        or di/tetrahydropyrimidinyl, these groups being optionally        substituted with one or more groups such as (C₁-C₄) alkyl, oxo        or thioxo; or the heterocycle represents the following group:

in which R′^(c), R′^(d), R′³, R′^(f), R′^(g) and R′^(h), which may beidentical or different, represent a hydrogen atom or a (C₁-C₄) alkylgroup, or else two groups R′^(g) with R′^(h), and/or R′^(e) with R′^(f),form an oxo or thioxo group, or else R′^(g) with R′^(e) together form acycloalkyl; and v represents an integer between 1 and 3 inclusive;preferably, R′^(c) to R′^(h) represent a hydrogen atom; and An⁻represents a counterion;

-   -   isothiouronium —C(NR′^(c)R′^(d))═N⁺R′^(e)R′^(f); An⁻ with        R′^(c), R′^(d), R′^(e) and R′^(f), which may be identical or        different, represent a hydrogen atom or a (C₁-C₄)alkyl group;        preferably, R′^(c) to R′^(f) represent a hydrogen atom; and An⁻        represents a counterion;    -   isothiourea —C(NR′^(c)R′^(d))═NR′^(e); with R′^(c), R′^(d), and        R′^(e) as defined above;    -   optionally substituted (di)aryl(C₁-C₄)alkyl, such as        9-anthracenylmethyl, phenylmethyl or diphenylmethyl optionally        substituted with one or more groups in particular chosen from        (C₁-C₄) alkyl, (C₁-C₄) alkoxy such as methoxy, hydroxyl,        (C₁-C₄)alkylcarbonyl and (di)(C₁-C₄)(alkyl)amino such as        dimethylamino;    -   optionally substituted (di)heteroaryl(C₁-C₄)alkyl, the        heteroaryl group is in particular cationic or noncationic, and        monocyclic, comprising 5 or 6 members and from 1 to 4        heteroatoms chosen from nitrogen, oxygen and sulphur, such as        the groups pyrrolyl, furanyl, thiophenyl, pyridyl, pyridyl        N-oxide such as 4-pyridyl or 2-pyridyl N-oxide, pyrylium,        pyridinium or triazinyl, optionally substituted with one or more        groups such as alkyl, particularly methyl, advantageously the        (di)heteroaryl(C₁-C₄)alkyl is (di)heteroarylmethyl or        (di)heteroarylethyl;    -   CR¹R²R³ with R¹, R² and R³, which may be identical or different,        representing a halogen atom or a group chosen from:        -   —(C₁-C₄) alkyl;        -   (C₁-C₄) alkoxy;        -   optionally substituted aryl, such as phenyl optionally            substituted with one or more groups such as (C₁-C₄)alkyl,            (C₁-C₄)alkoxy or hydroxyl;        -   optionally substituted heteroaryl, such as thiophenyl,            furanyl, pyrrolyl, pyranyl or pyridyl, optionally            substituted with a (C₁-C₄) alkyl group;        -   P(Z¹)R′¹R′²R′³ with R′¹ and R′², which may be identical or            different, representing a hydroxyl, (C₁-C₄)alkoxy or alkyl            group, R′³ representing a hydroxyl or (C₁-C₄)alkoxy group            and Z¹ representing an oxygen or sulphur atom;    -   a sterically hindered cyclic group such as the adamantyl group;        and    -   optionally substituted alkoxy(C₁-C₄)alkyl, such as methoxymethyl        (MOM), ethoxyethyl (EOM) or isobutoxymethyl.

According to a specific embodiment, the protected thiol fluorescent dyescomprising a heterocyclic group of formula (II) comprising a group Y i)which is a cationic, aromatic 5- or 6-membered monocyclic heteroarylgroup comprising from 1 to 4 heteroatoms chosen from oxygen, sulphur andnitrogen, such as oxazolium, isoxazolium, thiazolium, isothiazolium,1,2,4-triazolium, 1,2,3-triazolium, 1,2,4-oxazolium,1,2,4-thiadiazolium, pyrylium, pyridinium, pyrimidinium, pyrazinyl,pyrazinium, pyridazinium, triazinium, tetrazinium, oxazepinium,thiepinyl, thiepinium or imidazolium; ii) cationic 8- to 11-memberedbicyclic heteroaryl group, such as indolinium, benzoimidazolium,benzoxazolium or benzothiazolium, these monocyclic or bicyclicheteroaryl groups being optionally substituted with one or more groupssuch as alkyl, for instance methyl, or polyhalo(C₁-C₄)alkyl, forinstance trifluoromethyl; iii) or heterocyclic group below:

in which R′^(c) and R′^(d), which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkyl group; preferably, R′^(c) toR′^(d) represent a (C₁-C₄)alkyl group such as methyl; and An⁻ representsa counterion.

In particular, Y represents a group chosen from oxazolium, isoxazolium,thiazolium, isothiazolium, 1,2,4-triazolium, 1,2,3-triazolium,1,2,4-oxazolium, 1,2,4-thiadiazolium, pyrylium, pyridinium,pyrimidinium, pyrazinium, pyridazinium, triazinium, imidazolium,benzoimidazolium, benzoxazolium and benzothiazolium, these groups beingoptionally substituted with one or more (C₁-C₄) alkyl groups, inparticular methyl.

In particular, Y represents an alkali metal or a protecting group suchas:

-   -   (C₁-C₄)alkylcarbonyl, such as methylcarbonyl or ethylcarbonyl;    -   arylcarbonyl such as phenylcarbonyl;    -   (C₁-C₄)alkoxycarbonyl;    -   aryloxycarbonyl;    -   aryl(C₁-C₄)alkoxycarbonyl;    -   (di)(C₁-C₄)(alkyl)aminocarbonyl such as dimethyl-aminocarbonyl;    -   (C₁-C₄)(alkyl)arylaminocarbonyl;    -   optionally substituted aryl, such as phenyl;    -   5- or 6-membered monocyclic heteroaryl, such as imidazolyl or        pyridyl;    -   5- or 6-membered cationic monocyclic heteroaryl, such as        pyrylium, pyridinium, pyrimidinium, pyrazinium, pyridazinium,        triazinium or imidazolium; these groups being optionally        substituted with one or more identical or different (C₁-C₄)alkyl        groups, such as methyl;    -   8- to 11-membered cationic bicyclic heteroaryl, such as        benzoimidazolium or benzoxazolium; these groups being optionally        substituted with one or more identical or different (C₁-C₄)alkyl        groups, such as methyl;    -   cationic heterocycle of formula below:

-   -   isothiouronium —C(NH₂)═N⁺H₂; An⁻;    -   isothiourea —C(NH₂)═NH    -   SO₃ ⁻, M⁺ with M⁺ representing an alkali metal such as sodium or        potassium, or else M′ of formula (I) and M⁺ are absent.

According to a specific embodiment of the invention, the dyes of theinvention belong to one of the two formulae (Ia) and (IIa) which havethe ethylene group linking the pyridinium part to the phenyl at theortho- or para-position, i.e. at the 2-4′, 4-2′, 4-4′ positions:

in which formulae (Ia) or (IIa):

-   -   which may be identical or different, preferably identical,        represent a monocyclic, saturated or unsaturated heterocyclic        group comprising from 5 to 7 members and containing 1 or 2        heteroatoms chosen from nitrogen, oxygen and sulphur atoms, in        particular the heteroatom is a nitrogen atom; in particular, the        heterocycle is chosen from pyrazolyl, piperazinyl, piperidinyl,        morpholinyl and imidazolyl;    -   R_(i), R′_(i), R″_(i), and R′″_(i), which may be identical or        different, represent a hydrogen atom or a (C₁-C₄)alkyl group; in        particular, R_(i), R′_(i), R″_(i), and R′″_(i) represent a        hydrogen atom;    -   R_(g), R′_(g), R″_(g), R′″_(g), R_(h), R′_(h), R″_(h) and        R′″_(h), which may be identical or different, represent a        hydrogen atom or a C₁-C₄)alkyl group, in particular the R_(h)        and R′_(h), R″_(h) and R′″_(h) groups are in the ortho-position        with respect to the pyridinium and represent a (C₁-C₄)alkyl        group, and R_(g), R′_(g), R″_(g) and R′″_(g) represent a        hydrogen atom;    -   T_(a) and T_(b) represent a σ covalent bond or a group chosen        from: —N(R)—, —C(O)—N(R)—, —N(R)—C(O)—, —O—C(O)—, —C(O)—O— and        —N⁺(R)(R^(o))—, with R and R^(o), which may be identical or        different, representing a hydrogen atom or a C₁-C₄ alkyl group;        in particular, T_(a) and T_(b) represent a σ bond;    -   m, m′, n and n′, which may be identical or different, represent        an integer between 0 and 6 inclusive, with m+n and m′+n′        preferably identical, the sum m+n=m′+n′=an integer between 2 and        6 inclusive; preferably, m+n=m′+n′ is an integer equal to 2;    -   M′ represents an anionic counterion; and    -   Y is as defined above;    -   it being understood that:        -   the function SY of the dye of formula (IIa) may be in the            covalent form —S—Y or in the ionic form —S—Y+ depending on            the nature of Y and on the pH of the medium, and        -   when the compound of formula (Ia) or (IIa) contains other            cationic parts, it is associated with one or more anionic            counterions which allow the formula (Ia) or (IIa) to achieve            electroneutrality.

Advantageously, the dyes of formulae (Ia) and (IIa) have the formula

group in the para-position with respect to the phenyl linked to theethylene, i.e. in the 1′-position with respect to the phenyl radical,the ethylene being linked to the same phenyl radical in the 4′-position.

By way of example of thiol fluorescent dyes, mention may in particularbe made of the following compounds:

with M′ representing an anionic counterion.

The protected thiol dyes of formula (II″) can be synthesized in twostages. The first stage consists in preparing the nonprotected thiol dye(II′) according to the methods known to those skilled in the art, forinstance “Thiols and organic Sulfides”, “Thiocyanates andIsothiocyanates, organic”, Ullmann's Encyclopaedia, Wiley-VCH, Weinheim,2005. In addition, the second stage consists in protecting the thiolfunction according to the conventional methods known to those skilled inthe art for producing protected thiol dyes of formula (II″). By way ofexample for protecting the thiol function —SH of the thiol dye, use maybe made of the methods in the books “Protective Groups in OrganicSynthesis”, T. W. Greene, John Willey & Sons ed., NY, 1981, pp. 193-217;“Protecting Groups”, P. Kocienski, Thieme, 3rd ed., 2005, chap. 5.

This method can be illustrated by means of the method consisting i) ingenerating thiol fluorescent dyes of formula (II-H) by reduction of atwo-chromophore, heterocyclic, fluorescent dye bearing a disulphidefunction —S—S— (I′) and ii) in protecting, according to the conventionalmethods, said thiol function of (II-H) with the reactant 7 Y′R in orderto obtain the protected thiol fluorescent dyes of formula (II′). Thethiol compound 6 can also be metallated with an alkali metal or alkalineearth metal Met* so as to produce the thiolate fluorescent dye offormula (II″).

with Y′ representing a thiol-function-protecting group; Met*representing an alkali metal or an alkaline earth metal, particularlysodium or potassium, it being understood that, when the metal is analkaline earth metal, 2 chromophores comprising a thiolate function S⁻can be associated with one metal²⁺;with R₁, R₂, R₃, R₄, R_(g), R′_(g), R_(h), R′_(h), R_(i), R′_(i), m, n,het and M′ being as defined above; Y′ represents athiol-function-protecting group; and R represents a nucleofuge leavinggroup, for instance mesylate, tosylate, triflate or halide.

According to another possibility, a protected thiol compound (b)protected with a protecting group Y′ as defined above, preparedaccording to one of the procedures described in the books mentionedabove, said protected thiol compound comprising at least onenucleophilic function, can be reacted with a sufficient, preferablyequimolar, amount of a “reactive fluorescent chromophore” or a compoundcomprising such a “reactive fluorescent chromophore” (a). In otherwords, (a) comprises an electrophilic function for forming a Σ covalentbond, as can be illustrated schematically below in the preparation offluorescent dyes of formula (II′″):

with R₁, R₂, R₃, R₄, R_(g), R′_(g), R_(h), R′_(h), R_(i), R′_(i), m, n,het, Y′ and M′ as defined above; Nu representing a nucleophilic group; Erepresenting an electrophilic group; and Σ the bond generated afterattack by the nucleophile on the electrophile.

By way of example, the Σ covalent bonds that can be generated are listedin the table below based on condensation of electrophiles withnucleophiles:

Electrophiles E Nucleophiles Nu Σ covalent bonds Activated esters*Amines Carboxamides Acyl azides** Amines Carboxamides Acyl halidesAmines Carboxamides Acyl halides Alcohols Esters Acyl cyanides AlcoholsEsters Acyl cyanides Amines Carboxamides Alkyl halides AminesAlkylamines Alkyl halides Carboxylic acids Esters Alkyl halides ThiolsThioesters Alkyl halides Alcohols Ethers Sulphonic acids and ThiolsThioethers salts thereof Sulphonic acids and Carboxylic acids Esterssalts thereof Sulphonic acids and Alcohols Ethers salts thereofAnhydrides Alcohols Esters Anhydrides Amines Carboxamides Aryl halidesThiols Thioethers Aryl halides Amines Arylamines Aziridines ThiolsThioethers Carboxylic acids Amines Carboxamides Carboxylic acidsAlcohols Esters Carbodiimides Carboxylic acids N-acylureas or anhydridesDiazoalkanes Carboxylic acids Esters Epoxides Thiols ThioethersHaloacetamides Thiols Thioethers Imide esters Amines AmidinesIsocyanates Amines Ureas Isocyanates Alcools Urethanes IsothiocyanatesAmines Thioureas Maleimides Thiols Thioethers Sulphonic esters AminesAlkylamines Sulphonic esters Thiols Thioethers Sulphonic estersCarboxylic acids Esters Sulphonic esters Alcohols Ethers Sulphonylhalides Amines Sulphonamides *the activated esters of general formula—CO-Part with Part representing a leaving group such as oxysuccinimidyl,oxybenzotriazolyl, aryloxy which is optionally substituted; **the acylazides may rearrange to give isocyanates.

A variant of this process is to use a fluorescent chromophore having anelectrophilic acrylate function (—OCO—C═C—) on which is carried out anaddition reaction which will generate a Σ bond.

Use may also be made of a thiol reactant Y′—SH comprising a Y′ group asdefined above, the nucleophilic SH function of which can react with thecarbon atom in the alpha-position with respect to the halogen atom borneby the fluorescent chromophore (a′) so as to give the protected thiolfluorescent dye of formula (II′):

with R₁, R₂, R₃, R₄, R_(g), R′_(g), R_(h), R′_(h), T_(a), R_(i), R′_(i),m, n, het, Y′, (II′) and M′ being as defined above, and Hal representinga nucleofuge halogen atom such as bromine, iodine or chlorine.

More particularly, a nucleofuge leaving group may be substituted with athiourea group (S═C(NRR)NRR) so as to generate the isothiouroniums. Forexample, if the thiourea group is a thioimidazolinium (β), the reactionscheme is the following:

with R′_(c), R′_(d), R_(g), R′_(g), R_(h), R_(i), R′_(i), m, n, het,Hal, An and M′ being as defined above.

According to another variant, it is possible to generate an imidazolineintermediate from the halide comprising the fluorescent chromophore (a′)and a thioimidazoline (b′), so as to give, after alkylation with areactant R-Lg with R representing an alkyl group and Lg a leaving groupsuch as a halide, for instance chlorine, bromine or iodine, or amesylate or tosylate group.

A variant is to use, in place of the halide comprising the fluorescentchromophore (a′), a chromophore comprising another type of nucleofugesuch as tosylate or mesylate.

In accordance with another possibility, certain protective thiolfluorescent dyes (II′″) may be obtained by reacting a protected thiolcompound with a compound bearing two carboxylic acid functions which areactivated, according to the conventional methods (for example, reactionwith a carbodiimide or with thionyl chloride). The resulting product (d)is subsequently reacted with a fluorescent chromophore bearing anucleophilic function (c), for example of primary or secondary aminetype, or of aliphatic alcohol type.

with R₁, R₂, R₃, R₄, R_(g), R′_(g), R_(h), R′_(h), R_(i), het, T_(a),Y′, m, n, M′, E, Nu and (II′″) as defined above.

Another variant is to use a thiolactone as described below:

A synthesis variant is to combine the above pathway with the firstpathway, i.e., using two equivalents of the nucleophilic reactant (c)with a dielectrophilic disulphide reactant (j), it is possible togenerate, after condensation, the dichromophoric disulphide dye (I″), itbeing possible for the latter to undergo a reduction so as to form theheterocyclic fluorescent thiol dye which, in turn, can be eitherprotected so as to form the protected thiol fluorescent dye (II′″) or bemetallated with an alkali metal so as to give the metallatedheterocyclic thiol fluorescent dye (II′″_(metal)):

In accordance with another possibility, the protected thiol fluorescentdyes of formula (II′″) can be obtained by reaction of a compoundcomprising a thiol group protected with a Y′ group, and a hydroxyl groupactivated beforehand to a nucleofuge leaving group (d′), for instancemesylate, tosylate, triflate or halide, with a styrylpyridinechromophore (c′).

With R₁, R₂, R₃, R₄, R_(g), R′_(g), R_(h), R′_(h), R_(i), R′_(i), het,T_(a), Y′, m, n, (II′″) and E as defined above.

By way of example, a compound containing a protected thiol groupcontains a nucleofuge leaving group R, for instance mesylate, tosylateor triflate, which can undergo nucleophilic attack from the amine borneby the styryl fluorescent chromophore:

Another alternative comes from the use of halides as nucleofuge leavinggroup on a thiol compound that may be substituted with a primary aminefunction, for example, borne by a styryl fluorescent chromophore:

In accordance with another possibility, the thiol fluorescent dyes offormula (I) according to the invention may be obtained by reaction of acompound comprising a thiol group Y as defined above and anelectrophilic group (f) with a pyridinium compound comprising anucleophilic group. By way of example, an aldehyde, ketone orthioaldehyde, or a thioketone when G′ represents an oxygen or sulphuratom, may be condensed with an “activated methylene” such asalkylpyridinium (e) so as to generate a >C═C< ethylene bond. Thisreaction is commonly known as “Knoevenagel” condensation. The term“activated methylenes” is intended to mean those which preferentiallycomprise, in the 2- or 4-position with respect to the pyridinium group,a methylene group R_(i)—CH₂—:

with R₁, R₂, R₃, R₄, R_(a), R_(b), R_(g), R′_(g), R_(h), R′_(h), R_(i),R′₁, T_(a), het, m, n, Y and M′ as defined above and G representing anoxygen or sulphur atom.

Reference may be made to the book Advanced Organic Chemistry,“Reactions, Mechanisms and Structures”, J. March, 4th ed. John Willey &Sons, 1992 or T. W. Greene “Protective Groups in Organic Synthesis”, forfurther details on the operating conditions used for the processesmentioned above.

The thiol fluorescent dyes formed may be converted to —SY′ protectedthiol fluorescent dyes by protection of the —SH thiol using conventionalprotecting groups. The thiol fluorescent dyes are metallated by alsousing the conventional methods known to those skilled in the art, suchas those described in Advanced Organic Chemistry, “Reactions, Mechanismsand Structures”, J. March, 4th ed. John Willey & Sons, NY, 1992.

The protected thiol dyes can be deprotected by conventional routes suchas those described in the books “Protective Groups in OrganicSynthesis”, T. W. Greene, John Willey & Sons ed., NY, 1981; “ProtectingGroups”, P. Kocienski, Thieme, 3rd ed., 2005.

The starting reactants are commercially available or accessible byconventional methods known to those skilled in the art. By way ofexample, it is possible to synthesize the reactant (I′) using 2equivalents of pyridine derivative 1 and one equivalent of disulphidereactant comprising two leaving groups Gp, so as to give thedipyridinium disulphide salt 3 which can in turn be condensed with twoequivalents of aryl compound comprising an aldehyde/thioaldehyde group,f, to give I′.

with Lg representing a nucleofuge leaving group, for instance mesylate,tosylate, triflate or halide. The Lg⁻ counterions of the compounds (I′),above, can be replaced with M′ counterions of other natures, usingmethods known to those skilled in the art, in particular by ion exchangeresin.

The disymmetrical disulphide dyes of formula (I) can be synthesized in asingle stage by reacting a nonprotected thiol fluorescent dye with athiol fluorescent dye protected by Y′, so as to form the disulphide dyeof formula (I)

with R_(g), R′_(g), R″_(g), R′″_(g), R_(h), R′_(h), R″_(h), R′″_(h),R_(i), R′_(i), R″_(i), R′″R_(i), R₁, R′₁, R₂, R′₂, R₃, R′₃, R₄, R′₄, m,m′, n, n′, T_(a), T_(b), het, het′ and M′ as defined above; Y′represents a thiol-function-protecting group.

Reference may be made to the book Advanced Organic Chemistry,“Reactions, Mechanisms and Structures”, J. March, 4th ed. John Willey &Sons, 1992 or T. W. Greene “Protective Groups in Organic Synthesis”, forfurther details on the operating conditions used for the processesmentioned above.

The thiol fluorescent dyes formed can be converted to —SY′ protectedthiol fluorescent dyes by protection of the —SH thiol using conventionalprotecting groups. The thiol fluorescent dyes are metallated by alsousing the conventional methods known to those skilled in the art, suchas those described in Advanced Organic Chemistry, “Reactions, Mechanismsand Structures”, J. March, 4th ed. John Willey & Sons, NY, 1992.

The protected thiol dyes can be deprotected by conventional routes suchas those described in the books “Protective Groups in OrganicSynthesis”, T. W. Greene, John Willey & Sons ed., NY, 1981; “ProtectingGroups”, P. Kocienski, Thieme, 3rd ed., 2005.

The composition of the invention contains at least one fluorescent dyeof formula (I) or (II). In addition to the presence of at least onefluorescent dye of formula (I) or (II), the composition of the inventionmay also contain a reducing agent. This reducing agent may be chosenfrom thiols, for example cysteine, homocysteine or thiolactic acid, thesalts of these thiols, the phosphines, the bisulphite, the sulphites,thioglycolic acid, and also its esters, in particular glycerolmonothioglycolate, and thioglycerol. This reducing agent may also bechosen from borohydrides and derivatives thereof, for instance the saltsof borohydride, of cyanoborohydride, or triacetoxy-borohydride or oftrimethoxyborohydride: sodium salts, lithium salts, potassium salts,calcium salts, quaternary ammonium (tetramethylammonium,tetra-ethylammonium, tetra-n-butylammonium or benzyltriethyl-ammonium)salts; catechol borane.

The dye composition that can be used in the invention generally containsan amount of fluorescent dye of formula (I) or (II) of between 0.001%and 50% relative to the total weight of the composition. Preferably,this amount is between 0.005% and 20% by weight, and even morepreferably between 0.01% and 5% by weight, relative to the total weightof the composition.

The dye composition may also contain additional direct dyes. Thesedirect dyes are, for example, chosen from neutral, acidic or cationicnitrobenzene direct dyes, neutral, acidic or cationic azo direct dyes,tetraazapentamethine dyes, neutral, acidic or cationic quinone, inparticular anthraquinone dyes, azine direct dyes, triarylmethane directdyes, indoamine direct dyes and natural direct dyes.

Among the natural direct dyes, mention may be made of lawsone, juglone,alizarin, purpurin, carminic acid, kermesic acid, purpurogallin,protocatechaldehyde, indigo, isatin, curcumin, spinulosin andapigenindin. Extracts or decoctions containing these natural dyes, andin particular poultices or henna-based extracts, may also be used.

The dye composition may contain one or more oxidation bases and/or oneor more couplers conventionally used for dyeing keratin fibres.

Among the oxidation bases, mention may be made ofpara-phenylenediamines, bisphenylalkylenediamines, para-aminophenols,bis-para-aminophenols, ortho-amino-phenols, heterocyclic bases, andaddition salts thereof.

Among these couplers, mention may in particular be made ofmeta-phenylenediamines, meta-aminophenols, meta-diphenols, naphthalenecouplers, heterocyclic couplers, and addition salts thereof.

The coupler(s) is (are) each generally present in an amount of between0.001% and 10% by weight of the total weight of the dye composition,preferably between 0.005% and 6%.

The oxidation base(s) present in the dye composition is (are) in generaleach present in an amount of between 0.001% and 10% by weight of thetotal weight of the dye composition, preferably between 0.005% and 6% byweight.

In general, the addition salts of the oxidation bases and of thecouplers that can be used in the context of the invention are inparticular chosen from addition salts with an acid, such ashydrochlorides, hydrobromides, sulphates, citrates, succinates,tartrates, lactates, tosylates, benzenesulphonates, phosphates andacetates, and addition salts with a base, such as hydroxides of analkali metal such as sodium or potassium, aqueous ammonia, amines oralkanolamines.

The medium suitable for dyeing, also called dye support, is a cosmeticmedium generally constituted of water or of a mixture of water and atleast one organic solvent. By way of organic solvent, mention may, forexample, be made of C₁-C₄ lower alkanols, such as ethanol andisopropanol; polyols and polyol ethers, such as 2-butoxyethanol,propylene glycol, propylene glycol monomethyl ether, diethylene glycolmonoethyl ether and diethylene glycol monomethyl ether, and alsoaromatic alcohols such as benzyl alcohol or phenoxyethanol, and mixturesthereof.

The solvents, when they are present, are preferably present inproportions of preferably between 1% and 40% by weight approximately,relative to the total weight of the dye composition, and even morepreferably between 5% and 30% by weight approximately.

According to one variant, the invention contains a reducing agentcapable of reducing the disulphide bonds of keratin and/or of thefluorescent dye of formula (I). This reducing agent is as defined above.

The dye composition may also contain various adjuvants conventionallyused in hair-dyeing compositions, such as anionic, cationic, nonionic,amphoteric or zwitterionic surfactants or mixtures thereof, anionic,cationic, nonionic, amphoteric or zwitterionic polymers, or blendsthereof, mineral or organic thickeners, and in particular anionic,cationic, nonionic and amphoteric associative polymer thickeners,antioxidants, penetrating agents, sequestering agents, fragrances,buffers, dispersing agents, conditioning agents such as, for example,modified or unmodified, volatile or non-volatile silicones, such asamino silicones, film-forming agents, ceramides, preservatives,opacifiers or conductive polymers.

The above adjuvants are in general present in an amount, for each ofthem, of between 0.01% and 20% by weight relative to the weight of thecomposition.

Of course, those skilled in the art will take care to select this orthese possible additional compounds in such a way that the advantageousproperties intrinsically associated with the dye composition inaccordance with the invention are not, or are not substantially,impaired by the addition(s) envisaged.

The pH of the dye composition is generally between 4 and 14approximately, and preferably between 5 and 11 approximately. It may beadjusted to the desired value by means of acidifying or basifying agentsnormally used in the dyeing of keratin fibres or else by means ofconventional buffer systems.

Among the acidifying agents, mention may, by way of example, be made ofmineral or organic acids, such as hydrochloric acid, orthophosphoricacid, sulphuric acid, carboxylic acids, for instance acetic acid,tartaric acid, citric acid or lactic acid, or sulphonic acids.

Among the basifying agents, mention may, by way of example, be made ofaqueous ammonia, alkali carbonates, alkanolamines such as mono-, di- andtriethanolamines, and also derivatives thereof, sodium hydroxide orpotassium hydroxide and the compounds of formula (γ) below:

in which W_(a) is a propylene residue optionally substituted with ahydroxyl group or a C₁-C₄ alkyl radical; R_(a1), R_(a2), R_(a3) andR_(a4), which may be identical or different, represent a hydrogen atom,a C₁-C₄ alkyl radical or a C₁-C₄ hydroxyalkyl radical.

The dye composition may be in various forms, such as in the form of aliquid, a cream or a gel, or in any other form suitable for dyeingkeratin fibres, and in particular the hair.

According to a specific embodiment in the process of the invention, areducing agent may be applied as a pretreatment before the applicationof the composition containing at least one heterocyclic fluorescent dyeof formula (I) or (II).

This reducing agent may be chosen from thiols, for example cysteine,homocysteine or thiolactic acid, the salts of these thiols, thephosphines, the bisulphite, the sulphites, thioglycolic acid, and alsoits esters, in particular glyceryl monothioglycolate, and thioglycerol.This reducing agent may also be chosen from borohydrides and derivativesthereof, for instance the salts of borohydride, of cyanoborohydride, oftriacetoxyborohydride or of trimethoxyborohydride: sodium salts, lithiumsalts, potassium salts, calcium salts, quaternary ammonium(tetramethylammonium, tetra-ethylammonium, tetra-n-butylammonium,benzyltriethyl-ammonium) salts; catechol borane.

This pretreatment may be of short duration, in particular from 0.1second to 30 minutes, preferably from 1 minute to 15 minutes, with areducing agent as mentioned above.

According to another process, the composition comprising at least onefluorescent dye of formula (I) or (II) also contains at least onereducing agent as defined above. This composition is then applied to thehair.

According to another variant, the reducing agent is applied as apost-treatment, after the application of the composition containing atleast one thiol fluorescent dye (I). The duration of the post-treatmentwith the reducing agent may be short, for example from 0.1 second to 30minutes, preferably from 1 minute to 15 minutes, with a reducing agentas described above. According to a specific embodiment, the reducingagent is an agent of thiol or borohydride type as described above.

When the thiol fluorescent dye of formula (II) comprises athiol-function-protecting group Y, the process of the invention may bepreceded by a deprotection step aimed at restoring the SH function insitu.

By way of example, it is possible to deprotect the S—Y function with a Yprotecting group by adjusting the pH as follows:

Y: Protecting group Deprotection alkylcarbonyl pH > 9 arylcarbonyl pH >9 alkoxycarbonyl pH > 9 aryloxycarbonyl pH > 9 arylalkoxycarbonyl pH > 9(di)(alkyl)aminocarbonyl pH > 9 (alkyl)arylaminocarbonyl pH > 9optionally substituted aryl, such as phenyl pH > 9 5-, 6- or 7-memberedmonocyclic heteroaryl pH > 9 such as oxazolium 8- to 11-memberedbicyclic heteroaryl, such pH > 9 as benzoimidazolium or benzoxazolium

The deprotection step can also be carried out during a hair pretreatmentstep, for instance reducing pretreatment of the hair.

According to one variant, the reducing agent is added to the dyecomposition containing at least one fluorescent dye of formula (I) or(II) at the time of use.

A specific embodiment of the invention relates to a process in which thefluorescent dye of formula (I) or (II) can be applied directly to thehair without reducing agents, free of reducing pretreatment or reducingpost-treatment.

A treatment with an oxidizing agent may optionally be combined. Any typeof oxidant conventional in the field may be used. Thus, it may be chosenfrom hydrogen peroxide, urea peroxide, alkali metal bromates, persaltssuch as perborates and persulphates, and also enzymes, among whichmention may be made of peroxidases, 2-electron oxidoreductases such asuricases and 4-electron oxygenases such as laccases. The use of hydrogenperoxide is particularly preferred.

This oxidizing agent can be applied to the fibres before or after theapplication of the composition containing at least one fluorescent dyeof formula (I) or (II).

The application of the dye composition according to the invention isgenerally carried out at ambient temperature. It may, however, becarried out at temperatures ranging from 20 to 180° C.

A subject of the invention is also a multicompartment device or dyeingkit in which a first compartment contains a dye composition comprisingat least one fluorescent dye of formula (I) or (II) and a secondcompartment contains a reducing agent capable of reducing the disulphidefunctions of keratin materials and/or the fluorescent dye of formula(I).

One of these compartments may also contain one or more other dyes ofdirect dye or oxidation dye type.

The invention also relates to a multicompartment device in which a firstcompartment contains a dye composition comprising at least onefluorescent dye of formula (I) or (II); a second compartment contains areducing agent capable of reducing the disulphide bond of keratinmaterials and/or the fluorescent dye of formula (I); and a thirdcompartment contains an oxidizing agent.

Alternatively, the dyeing device contains a first compartment containinga dye composition which comprises at least one protected thiolfluorescent dye of formula (II) and a second compartment containing anagent capable of deprotecting the protected thiol so as to free thethiol.

Each of the devices mentioned above may be equipped with a means fordelivering the desired mixture to the hair, for example such as thedevices described in patent FR 2 586 913.

The examples which follow serve to illustrate the invention without,however, being limiting in nature. The fluorescent dyes of the exampleshereinafter have been entirely characterized by conventionalspectroscopic and spectrometric methods.

EXAMPLES Synthesis Examples Example 1 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis{4-[(E)-2-(4-pyrrolidin-1-ylphenyl)vinyl]-pyridinium}dimethanesulphonate [1]

Synthesis Scheme

Stage 1: Synthesis of disulphanediyldiethane-2,1-diyl dimethanesulphonate

10 g of 2,2′-dithiodiethanol and 14.44 g of triethylamine (TEA) arediluted in 100 ml of ethyl acetate (EtOAc). At 0° C., 16.35 g ofmethanesulphonyl chloride diluted in 35 ml of EtOAc are added dropwiseto the reaction medium with rapid stirring. 7.22 g of TEA areintroduced, and the stirring is continued at ambient temperature for 4 h30. 8.2 g of methanesulphonyl chloride are added dropwise at 15° C., andthen the stirring is maintained at ambient temperature for 17 h. Theprecipitate is filtered off and washed with 3 times 50 ml of EtOAc. Theorganic phases are extracted with 100 ml of ice-cold water, 100 ml ofwater, 3 times 50 ml of a saturated solution of sodium bicarbonate(NaHCO₃), with twice 20 ml of a saturated solution of sodium chloride(NaCl), and are then dried over anhydrous sodium sulphate (Na₂SO₄). TheEtOAc is evaporated off, and 17.49 g of pale yellow translucent oil arerecovered and stored at −25° C. The analyses indicate that the productis in conformity and pure.

Stage 2: Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis(4-methylpyridinium)dimethanesulphonate

3.51 g of picoline and 5 g of disulphanediyldiethane-2,1-diyl dimethanesulphonate are diluted in 5 ml of N-methylpyrrolidinone (NMP) and thenheated at 80° C. for 2 h with stirring. The stirring is maintained atambient temperature for 17 h. The reaction medium is made up with 50 mlof EtOAc, and then filtered, washed with 3 times 100 ml of EtOAc, anddried under vacuum in the presence of P₂O₅. 7.29 g of brown powder arerecovered. The analyses indicate that the product is in conformity andpure.

Stage 3: Synthesis of1,1′-(disulfanediyldiéthane-2,1-diyl)-bis{4-[(E)-2-(4-pyrrolidin-1-ylphenyl)vinyl]-pyridinium}dimethanesulphonate [1]

3.42 g of 4-(1-pyrrolidino)benzaldehyde, 10 ml of isopropanol (iPrOH)and 1.69 ml of pyrrolidine are mixed for 10 minutes with stirring. 1.18ml of acetic acid are added and the mixture is stirred at ambienttemperature for 20 minutes. 5 g of1,1′-(disulphane-diyldiethane-2,1-diyl)bis(4-methylpyridinium)dimethanesulphonate in suspension in 7 ml of iPrOH and 2 ml of methanol areadded. The reaction mixture is kept stirring for 24 h at ambienttemperature. The precipitate obtained is filtered off, washed with 100ml of acetone and then dried. 7.24 g of powder are recovered. Theanalyses indicate that the product is in conformity and pure. ¹H NMR(400 MHz, MeOH-d4) 2.03-2.06 (m, 8H), 2.71 (s, 6H), 3.3-3.4 (m, 12H),4.7 (t, 4H), 6.6 (d, 4H), 6.99 (d, 2H), 7.57 (d, 4H), 7.8 (d, 2H), 7.93(d, 4H), 8.53 (d, 4H).

Example 2 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis{4-[(E)-2-(4-piperazin-1-ylphenyl)vinyl]pyridinium}dimethanesulphonate[2]

Synthesis Scheme

Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis{4-[(E)-2-(4-piperazin-1-ylphenyl)vinyl]-pyridinium}dimethanesulphonate[2]

2.5 g of 4-piperazin-1-yl-benzaldehyde, 10 ml of iPrOH, and 1.06 ml ofpyrrolidine are mixed for 10 minutes with stirring. 0.74 ml of aceticacid are added and the mixture is stirred at ambient temperature for 20minutes. 3.22 g of1,1′-(disulphanediyldiethane-2,1-diyl)bis(4-methylpyridinium)dimethanesulphonatein suspension in 7 ml of iPrOH and 2 ml of methanol are added. Thereaction mixture is kept stirring for 24 h at ambient temperature. 100μl of pyrrolidine and 70 μl of acetic acid are added, the stirring ismaintained at ambient temperature for 48 h. The precipitate obtained isfiltered off, washed with 100 ml of acetone and then dried. 516 mg ofpowder are recovered. The analyses indicate that the product is inconformity and pure. ¹H NMR (400 MHz, MeOH-d₄) 3.17 (m, 8H), 3.4 (t,4H), 3.46 (m, 8H), 4.81 (t, 4H), 7.04 (d, 4H), 7.21 (d, 2 H), 7.67 (d,4H), 7.88 (d, 2H), 8.08 (d, 4H), 8.69 (d, 4H)

Example 3 Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis{2-[(E)-2-(4-pyrrolidin-1-ylphenyl)vinyl]pyridinium}dibromide[3]

Synthesis Scheme

Stage 1: Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis(2-methylpyridinium)dibromide

A mixture of 56 g of 1-bromo-2-[(2-bromoethyl)-disulphanyl]ethane and 15ml of N-methylpyrrolidone (NMP) is poured dropwise onto 35 g of2-picoline with stirring, at 80° C. The mixture (white suspension) iskept stirring at 80° C. for 30 min, 100 ml of acetonitrile (ACN) areadded, and the stirring is maintained at 80° C. for 90 min. Aftercooling, the solid obtained is filtered off, washed with 100 ml of ACNand then dried. 56.2 g of brown powder are recovered. 45 g of thispowder are suspended in 300 ml of isopropanol (iPrOH), at reflux. Oncethe temperature has dropped to 40° C., the solid is filtered off, washedwith 3 times 100 ml of iPrOH and dried under vacuum. 40.56 g of a lightbeige product are obtained. The analyses are in conformity with theexpected structure.

Stage 2: Synthesis of1,1′-(disulphanediyldiethane-2,1-diyl)bis{2-[(E)-2-(4-pyrrolidin-1-ylphenyl)-vinyl]pyridinium}dibromide[3]

2 g of 4-pyrrolidin-1-yl-benzaldehyde solubilized in 4 ml of iPrOH and0.93 ml of pyrrolidine are stirred at ambient temperature for 10 min.0.65 ml of acetic acid are added to the reaction medium, which is keptstirring at ambient temperature for 20 min. 2.65 g of1,1′-(disulphanediyldiethane-2,1-diyl)bis(2-methyl-pyridinium)dibromidepreviously solubilized in 5 ml of iPrOH and 2 ml of methanol areintroduced into the medium. The stirring is maintained at 20° C. for 17h. 20 ml of iPrOH are added and the stirring is maintained at ambienttemperature for 4 days. The precipitate is filtered off, and the redpowder obtained is solubilized with 50 ml of iPrOH under hot conditionsand with stirring. The precipitate obtained is filtered off under hotconditions and then dried. 2.20 g of red powder are recovered. Theanalyses indicate that the product is in conformity and pure. ¹H NMR(400 MHz, DMSO-d₆) 1.93 (m, 8H), 3.15 (t, 4H), 3.22 (m, 8H), 4.89 (t,4H), 6.48 (d, 4H), 7.05 (d, 2H), 7.51-7.56 (dd and d, 6H), 7.69 (d, 2H),8.16-8.25 (d and dd, 4H), 8.5 (d, 2H).

Example 4 Synthesis of1,1′-{disulphanediylbis[ethane-2,1-diylimino(2-oxoethane-2,1-diyl)]}bis{4-[(E)-2-(4-pyrrolidin-1-ylphenyl)vinyl]pyridinium}dichloride[4]

Synthesis Scheme

Stage 1: Synthesis ofN,N′-(disulphanediyldiethane-2,1-diyl)bis(2-chloroacetamide)

40.3 g of cystamine dihydrochloride are dissolved in 100 ml of water, 32ml of sodium hydroxide at 35% are added (pH 9.7) and the temperature isreduced to 5° C. 33.5 ml of chloroacetyl chloride are introduceddropwise, while maintaining the temperature at below 10° C. andmaintaining the pH between 7.9 and 9.3 by adding sodium hydroxide. Themedium is kept stirring at ambient temperature for 2 h. The precipitateis filtered off, washed with 5×150 ml of water, and then dried undervacuum in the presence of P₂O₅. 35.3 g of white powder are recovered.The analyses indicate that the product is in conformity.

Stage 2: Synthesis of1,1′-{disulphanediylbis[ethane-2,1-diylimino(2-oxoethane-2,1-diyl)]}bis(4-methyl-pyridinium)dichloride

6.1 g of N,N′-(disulphanediyldiethane-2,1-diyl)bis(2-chloroacetamide)and 4.5 g of 4-picoline are dissolved in 50 ml of NMP and brought to 80°C. for 19 h. After cooling of the mixture via successive precipitationsin acetone and drying under vacuum, 9.2 g of salts are recovered. Theanalyses show that the product is in conformity. ¹H NMR (400 MHz, D₂O):2.61 (s, 6H), 2.82 (t, 4H), 3.56 (t, 4H), 5.31 (s, 4H), 7.85 (d, 4H),8.51 (d, 4H).

Stage 3: Synthesis of1,1′-{disulphanediylbis[ethane-2,1-diylimino(2-oxoethane-2,1-diyl)]}bis{4-[(E)-2-(4-pyrrolidin-1-ylphenyl)vinyl]pyridinium}dichloride[4]

700 mg of 4-pyrrolidin-1-ylbenzaldehyde, 328 μl of pyrrolidine, 232 μlof acetic acid and 490 mg of1,1′-{disulphanediylbis[ethane-2,1-diylimino-(2-oxoethane-2,1-diyl)]}bis(4-methylpyridinium)dichlorideare solubilized in 10 ml of isopropanol and kept stirring at ambienttemperature for 3 h 30 min. The mixture is poured into 50 ml of 1:1dichloromethane/acetone solution. A solid precipitates. It is filteredoff, washed with three times 20 ml of acetone and dried under vacuum.620 mg of black powder are recovered. The analyses show that the productis in conformity (LCMS: 100%; mass peak m/z=367, corresponding to thedication).

Example 5 Synthesis of4-[(E)-2-(4-pyrrolidin-1-yl-phenyl)vinyl]-1-(2-sulphanylethyl)pyridiniummethane-sulphonate [5]

Synthesis of the4-[(E)-2-(4-pyrrolidin-1-ylphenyl)vinyl]-1-(2-sulphanylethyl)pyridiniumsalt [5] Synthesis Scheme

81 mg of compound [2] are dissolved in 10 ml of water/ethanol mixture(1/1). 60 mg (2 eq.) of 3-[bis(2-carboxyethyl)phosphino]propanoic acidhydrochloride hydrate in solution in 1 ml of water and 21 mg (4 eq.) ofsodium bicarbonate in solution in 1 ml of water are added to themixture. After stirring at 40° C. for 30 minutes under an inertatmosphere, the analyses indicate that the mixture contains verypredominantly the expected product [5].

LC-MS analysis: LC-DAD (400-700 nm)

Column: Waters XTerra MS C18 5 μm (4.6×50) mm

Mobile phase: A: water+0.1% formic acid/B: acetonitrile

Linear gradient: T (min) A %/B %: 0 min 95/5; 8 min 0/100

Flow rate: 1 ml/min

Detection: UV diode array λ=400-700 nm

Retention time t=4.9 min

Relative purity>95%

MS (ESI+) m/z=311 corresponds to the mass peak for the monocation of theexpected product [5]

Dyeing Example Dyeing Process—Compounds [1] to [3] Preparation of aComposition A

Disulphide dye from [1] to [3] 10⁻³ mol % Benzyl alcohol 4 gPolyethylene glycol 60 EO 6 g Hydroxyethylcellulose 0.7 gAlkylpolyglucoside in an 4.5 g aqueous solution containing 65% AMDemineralized water qs 100 g

Preparation of a Composition B

Thioglycolic acid 1M Sodium hydroxide qs pH 8.5 Demineralized water qs100 g

At the time of use, compositions A (9 ml) and B (1 ml) are mixed, thenthe mixture obtained is applied to a lock of 1 g of dark hair (toneheight 4) for 30 minutes at ambient temperature (the locks are turnedover and reimpregnated after 15 minutes).

After rinsing with running water and drying, lightening of the hair thustreated is observed: the lock of tone height 4 has become visuallylighter than untreated control locks.

Dyeing Process—Compound [5]

10 ml of fresh solution of compound [5] of synthesis example [5] areapplied to a lock of 1 g of hair of tone height 4 placed at the bottomof the same bowl for 30 minutes at ambient temperature (the locks areturned over and reimpregnated after 15 minutes).

The locks are subsequently rinsed with running water and dried.

After dyeing, the lock of tone height 4 has become visually lighter thanuntreated control locks.

Remanence with Respect to Successive Shampooing Operations:

The locks thus treated are divided into two, half are subjected to 5successive shampooing operations according to a cycle which compriseswetting the locks with water, washing with a conventional shampoo,rinsing with water, followed by drying.

Visual Observations

During the shampooing operations, there is no visible bleeding, theshampoo foam and the rinsing water are not coloured.

The lightening effect remains visible on the hair of tone height 4 thustreated.

Results in the L*a*b* System:

The colour of the locks before and after the 5 washes was evaluated inthe L*a*b* system by means of a KONICA MINOLTA® CM 2600Dspectrophotometer, (illuminant D65).

In this L*a*b* system, L* represents the colour intensity, a* indicatesthe green/red colour axis and b* the blue/yellow colour axis. The higherthe value of L, the lighter or weaker a colour, conversely, the lowerthe value of L, the darker or much stronger the colour. The higher thevalue of a*, the redder the shade, and the higher the value of b*, themore yellow the shade.

The variation in colouring between the TH4 locks of hair and the locksof hair after treatment (dyeing, or dyeing and successive washingoperations) is measured by (ΔE) according to the following equation:

ΔE=√{square root over ((L*−L ₀*)²+(a*−a ₀*)²+(b*−b ₀*)²)}{square rootover ((L*−L ₀*)²+(a*−a ₀*)²+(b*−b ₀*)²)}{square root over ((L*−L₀*)²+(a*−a ₀*)²+(b*−b ₀*)²)}

In this equation, L*, a* and b* represent the values measured beforedyeing, and L₀*, a₀* and b₀* represent the values measured aftertreatment (dyeing, or dyeing and successive washing operations).

The greater the value of ΔE, the greater the difference in colourbetween TH4 locks and the coloured locks.

Treatment with the fluorescent dye on the TH4 locks ΔE After applicationof compound 1 according to the 4.13 invention After application ofcompound 1 according to the 4.30 invention and after 5 successiveshampooing operations After application of compound 2 according to the5.09 invention After application of compound 2 according to the 6.32invention and after 5 successive shampooing operations After applicationof compound 3 according to the 6.23 invention After application ofcompound 3 according to the 6.02 invention and after 5 successiveshampooing operations After application of compound 5 according to the3.02 invention After application of compound 5 according to the 4.64invention and after 5 successive shampooing operations

The results in the table show that there is no significant difference incolour variation even after 5 shampooing operations. Thus, the coloringand the lightening effect on the hair remains virtually unchanged, whichshows a very good resistance to shampooing of the dyes of the invention.

Reflectance Results:

The lightening effectiveness of the compositions in accordance with theinvention and the remanance of said compositions with respect tosuccessive shampooing operations were expressed as a function of thereflectance of the hair. These reflectances are compared with thereflectance of a lock of untreated hair of tone height TH4.

The reflectance is measured by means of a KONIKA-MINOLTA® CM 2600dspectrophotocolorimeter apparatus and after irradiation of the hair withvisible light in the wavelength range of from 400 to 700 nanometres.

It can first of all be seen from FIGS. 1 and 2 that the reflectance of alock of hair treated with a composition according to the invention isgreater than that of the untreated hair. The treated locks thereforeappear to be lighter.

Furthermore, according to the results, FIGS. 1 and 2 show that thereflectance of the locks of hair of tone height 4, treated with thecomposition of the invention, change very little even after 5 shampooingoperations. Thus, the colouring and the lightening effect on the hairremain virtually unchanged, which shows a very good resistance of thedyes of the invention to shampooing operations.

1-23. (canceled)
 24. At least one fluorescent entity chosen from thoseof formula (I) and (II):

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates thereof; wherein:

which may be identical or different, represent a saturated orunsaturated heterocyclic group; R_(g), R′_(g), R″_(g), R′″_(g), R_(h),R′_(h), R″_(h) and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom identical to ordifferent from that of the nitrogen atom; R′_(i), R′″_(i), and R″″_(i),which may be identical or different, represent a hydrogen atom or a(C₁-C₄) alkyl group; R₁, R′₁, R₂, R′₂, R₃, R′₃, R₄ and R′₄, which may beidentical or different, represent a hydrogen atom or a (C₁-C₄)alkyl,(C₁-C₄)alkoxy, hydroxyl, cyano, carboxyl, amino, (C₁-C₄)alkylamino or(C₁-C₄) dialkylamino group, it being possible for said alkyl radicals toform, with the nitrogen atom which bears them, a heterocycle comprisingfrom 5 to 7 members, optionally comprising another heteroatom which mayor may not be different from nitrogen; T_(a) and T_(b), which may beidentical or different, represent: a σ covalent bond; at least oneradical chosen from —SO₂—, —O—, —S—, —N(R)—, —N⁺(R)(R^(o))— and —C(O)—,wherein R and R^(o), which may be identical or different, represent ahydrogen atom, a C₁-C₄ alkyl radical, a C₁-C₄ hydroxyalkyl radical or anaryl(C₁-C₄)alkyl; or at least one cationic or noncationic,heterocycloalkyl or heteroaryl radical; m, m′, n and n′, which may beidentical or different, represent an integer ranging from 0 to 6,wherein m+n and m′+n′, which may be identical or different, represent aninteger ranging from 1 to 10; M′ represents an anionic counterion; and Yrepresents: i) a hydrogen atom; ii) an alkali metal; iii) an alkalineearth metal; iv) an ammonium group: N⁺R^(α)R^(β)R^(γ)R^(δ) or aphosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(α), R^(β), R^(γ) andR^(δ), which may be identical or different, representing a hydrogen atomor a (C₁-C₄)alkyl group; or v) a thiol-function-protecting group; itbeing understood that when the at least one entity chosen from those offormulae (I) and (II) contains other cationic parts, it is associatedwith at least one anionic counterion allowing the at least one entitychosen from those of formulae (I) and (II) to achieve electroneutrality.25. The at least one fluorescent entity of formula (II) according toclaim 24, wherein Y represents a hydrogen atom or an alkali metal. 26.The at least one fluorescent entity of formula (II) according to claim24, wherein Y represents a protecting group.
 27. The at least onefluorescent entity of formula (II) according to claim 26, wherein Yrepresents a protecting group chosen from the following radicals:(C₁-C₄)alkylcarbonyl; (C₁-C₄)alkylthiocarbonyl; (C₁-C₄)alkoxycarbonyl;(C₁-C₄)alkoxythiocarbonyl; (C₁-C₄)alkylthiothiocarbonyl;(di)(C₁-C₄)(alkyl)aminocarbonyl; (di)(C₁-C₄)(alkyl)aminothiocarbonyl;arylcarbonyl; aryloxycarbonyl; aryl(C₁-C₄)alkoxycarbonyl;(di)(C₁-C₄)(alkyl)aminocarbonyl; (C₁-C₄)(alkyl)arylaminocarbonyl;carboxyl; SO₃ ⁻M⁺ with M⁺ representing an alkali metal or alternativelySO₃ ⁻M′ with M′ representing an anionic counterion; optionallysubstituted aryl; optionally substituted heteroaryl; optionallycationic, optionally substituted heterocycloalkyl; a heterocycle:

wherein R′^(c), R′^(d), R′^(e), R′^(f), R′^(g) and R′^(h), which may beidentical or different, represent a hydrogen atom or a (C₁-C₄) alkylgroup, or else two groups R′^(g) with R′^(h), and/or R′^(e) with R′^(f),form an oxo or thioxo group, or else R′^(g) with R′^(e) together form acycloalkyl; and v represents an integer ranging from 1 to 3;isothiouronium —C(NR′^(c)R′^(d))═N⁺R′^(e)R′^(f); An⁻ wherein R′^(c),R′^(d), R′^(e) and R′^(f), which may be identical or different,represent a hydrogen atom or a (C₁-C₄)alkyl group; and An⁻ represents acounterion; isothiourea —C(NR′^(c)R′^(d))═NR′^(e); wherein R′^(c),R′^(d) and R′^(e), which may be identical or different, represent ahydrogen atom or a (C₁-C₄)alkyl group; optionally substituted(di)aryl(C₁-C₄)alkyl; optionally substituted (di)heteroaryl(C₁-C₄)alkyl;CR¹R²R³ with R¹, R² and R³, which may be identical or different,representing a halogen atom or a group chosen from: (C₁-C₄)alkyl;(C₁-C₄)alkoxy; optionally substituted aryl; optionally substitutedheteroaryl; P(Z¹)R′¹R′²R′³ with R′¹ and R′², which may be identical ordifferent, representing a hydroxyl, (C₁-C₄)alkoxy or alkyl group, R′³representing a hydroxyl or (C₁-C₄)alkoxy group and Z¹ representing anoxygen or sulphur atom; a sterically hindered cyclic group; oroptionally substituted alkoxy(C₁-C₄)alkyl.
 28. The at least onefluorescent entity of formula (II) according to claim 24, wherein Yrepresents an alkali metal or a protecting group chosen from:(C₁-C₄)alkylcarbonyl; arylcarbonyl; (C₁-C₄)alkoxycarbonyl;aryloxycarbonyl; aryl(C₁-C₄)alkoxycarbonyl;(di)(C₁-C₄)(alkyl)aminocarbonyl; (C₁-C₄)(alkyl)arylaminocarbonyl;optionally aryl; 5- or 6-membered cationic monocyclic heteroaryl; 8- to11-membered cationic bicyclic heteroaryl; cationic heterocycle offormula:

isothiouronium —C(NH₂)═N⁺H₂; An⁻; isothiourea —C(NH₂)═NH; and SO₃ ⁻; M⁺with M⁺ representing an alkali metal or alternatively SO₃-M′ with M′representing an anionic counterion.
 29. The at least one fluorescententity according to claim 24, chosen from those of formula (Ia) and(IIb):

wherein:

which may be identical or different, represent a monocyclic, saturatedor unsaturated heterocyclic group comprising from 5 to 7 members andcontaining one or two heteroatoms chosen from nitrogen, oxygen andsulphur atoms; R_(i), R′₁, R″_(i); and R′″_(i) which may be identical ordifferent, represent a hydrogen atom or a (C₁-C₄) alkyl group; R_(g),R′_(g), R″_(g), R′″_(g), R_(h), R′_(h), R″_(h) and R′″_(h), which may beidentical or different, represent a hydrogen atom or a (C₁-C₄)alkylgroup; T_(a) and T_(b), represent a σ covalent bond or a group chosenfrom: —N(R)—, —C(O)—N(R)—, —N(R)—C(O)—, —O—C(O)—, —C(O)—O— and—N⁺(R)(R^(o)—, wherein R and R^(o) which may be identical or different,represent a hydrogen atom or a C₁-C₄ alkyl group; m, m′, n and n′, whichmay be identical or different, represent an integer ranging from 0 to 6,wherein the sums m+n and m′+n′ are integers ranging from 2 to 4; M′represents an anionic counterion; and Y represents: i) a hydrogen atom;ii) an alkali metal; iii) an alkaline earth metal; iv) an ammoniumgroup: N⁺R^(α)R^(β)R^(γ)R^(δ) or a phosphonium group:P⁺R^(α)R^(β)R^(γ)R^(δ) with R^(α), R^(β), R^(γ) and R^(δ), which may beidentical or different, representing a hydrogen atom or a (C₁-C₄)alkylgroup; or v) a thiol-function-protecting group; it being understoodthat: when the compound of formula (Ia) or (IIb) contains other cationicparts, it is associated with at least one anionic counterion whichallows formula (Ia) or (IIa) to achieve electroneutrality.
 30. The atleast one fluorescent entity according claim 29 belonging to formula(Ia) or (IIb) having the

groups in the 1′-position with respect to the phenyl, the ethylene beinglinked to the same phenyl in the 4′-position.
 31. The at least onefluorescent entity according to claim 24, chosen from those of formulae1-16:

wherein M′ represents an anionic counterion.
 32. A dye compositioncomprising, in a suitable cosmetic medium, at least one fluorescententity chosen from those of formulae (I) and (II)

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates thereof; wherein:

which may be identical or different, represent a saturated orunsaturated heterocyclic group; R_(g), R′_(g), R″_(g), R′″_(g), R_(h),R′_(h), R″_(h) and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom identical to ordifferent from that of the nitrogen atom; R_(i), R′_(i), R′″_(i), andR″″_(i) which may be identical or different, represent a hydrogen atomor a (C₁-C₄) alkyl group; R₁, R′₁, R₂, R′₂, R₃, R′₃, R₄ and R′₄, whichmay be identical or different, represent a hydrogen atom or a(C₁-C₄)alkyl, (C₁-C₄)alkoxy, hydroxyl, cyano, carboxyl, amino,(C₁-C₄)alkylamino or (C₁-C₄) dialkylamino group, it being possible forsaid alkyl radicals to form, with the nitrogen atom which bears them, aheterocycle comprising from 5 to 7 members, optionally comprisinganother heteroatom which may or may not be different from nitrogen;T_(a) and T_(b), which may be identical or different, represent: a σcovalent bond; at least one radical chosen from —SO₂—, —O—, —S—, —N(R)—,—N⁺(R)(R^(o))— and —C(O)—, wherein R and R^(o), which may be identicalor different, represent a hydrogen atom, a C₁-C₄ alkyl radical, a C₁-C₄hydroxyalkyl radical or an aryl(C₁-C₄)alkyl; or at least one cationic ornoncationic, heterocycloalkyl or heteroaryl radical; m, m′, n and n′,which may be identical or different, represent an integer ranging from 0to 6, wherein m+n and m′+n′, which may be identical or different,represent an integer ranging from 1 to 10; M′ represents an anioniccounterion; and Y represents: i) a hydrogen atom; ii) an alkali metal;iii) an alkaline earth metal; iv) an ammonium group:N⁺R^(α)R^(β)R^(γ)R^(δ) or a phosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ)with R^(α), R^(β), R^(γ) and R^(δ), which may be identical or different,representing a hydrogen atom or a (C₁-C₄)alkyl group; or v) athiol-function-protecting group; it being understood that when the atleast one entity chosen from those of formulae (I) and (II) containsother cationic parts, it is associated with at least one anioniccounterion allowing the at least one entity chosen from those offormulae (I) and (II) to achieve electroneutrality.
 33. The dyecomposition of claim 32, further comprising at least one reducing agent.34. The dye composition according to claim 33, wherein the at least onereducing agent is chosen from cysteine and salts thereof, homocysteineand salts thereof, thiolactic acid and salts thereof, phosphines,bisulphite, sulphites, thioglycolic acid and its esters, borohydridesand derivatives thereof, sodium salts, lithium salts, potassium salts,calcium salts, quaternary ammonium salts, and catechol borane.
 35. Thedye composition according to claim 32, wherein the at least onefluorescent entity is present in an amount ranging from 0.001% to 50% byweight, relative to the total weight of the composition.
 36. A processfor dyeing keratin materials, comprising: applying to the keratinmaterials at least one dye composition comprising, in a suitablecosmetic medium, at least one fluorescent entity chosen from formulae(I) and (II)

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates thereof; wherein:

which may be identical or different, represent a saturated orunsaturated heterocyclic group; R_(g), R′_(g), R″_(g), R′″_(g), R_(h),R′_(h), R″_(h) and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom identical to ordifferent from that of the nitrogen atom; R_(i), R′_(i), R′″_(i), andR″″_(i), which may be identical or different, represent a hydrogen atomor a (C₁-C₄) alkyl group; R₁, R′₁, R₂, R′₂, R₃, R′₃, R₄ and R′₄, whichmay be identical or different, represent a hydrogen atom or a(C₁-C₄)alkyl, (C₁-C₄)alkoxy, hydroxyl, cyano, carboxyl, amino,(C₁-C₄)alkylamino or (C₁-C₄) dialkylamino group, it being possible forsaid alkyl radicals to form, with the nitrogen atom which bears them, aheterocycle comprising from 5 to 7 members, optionally comprisinganother heteroatom which may or may not be different from nitrogen;T_(a) and T_(b), which may be identical or different, represent: a σcovalent bond; at least one radical chosen from —SO₂—, —O—, —S—, —N(R)—,—N⁺(R)(R^(o))— and —C(O)—, wherein R and R^(o), which may be identicalor different, represent a hydrogen atom, a C₁-C₄ alkyl radical, a C₁-C₄hydroxyalkyl radical or an aryl(C₁-C₄)alkyl; or at least one cationic ornoncationic, heterocycloalkyl or heteroaryl radical; m, m′, n and n′,which may be identical or different, represent an integer ranging from 0to 6, wherein m+n and m′+n′, which may be identical or different,represent an integer ranging from 1 to 10; M′ represents an anioniccounterion; and Y represents: i) a hydrogen atom; ii) an alkali metal;iii) an alkaline earth metal; iv) an ammonium group:N⁺R^(α)R^(β)R^(γ)R^(δ) or a phosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ)with R^(α), R^(β), R^(γ) and R^(δ), which may be identical or different,representing a hydrogen atom or a (C₁-C₄)alkyl group; or v) athiol-function-protecting group; it being understood that when the atleast one entity chosen from those of formulae (I) and (II) containsother cationic parts, it is associated with at least one anioniccounterion allowing the at least one entity chosen from those offormulae (I) and (II) to achieve electroneutrality; and optionallyapplying at least one reducing agent.
 37. The dyeing process accordingto claim 36, wherein, when the at least one fluorescent entity offormula (II) comprises a protecting group Y, the application is precededby a deprotection step.
 38. The dyeing process according to claim 36,wherein the keratin materials are dark keratin fibers.
 39. The dyeingprocess according to claim 38, wherein the keratin materials are darkkeratin fibers having a tone height of less than or equal to
 6. 40. Thedyeing process according to claim 36, comprising applying at least onereducing agent before or after applying the composition comprising atleast one fluorescent entity.
 41. The dyeing process according to claim36, wherein the composition further comprises at least one oxidizingagent.
 42. The dyeing process according to claim 36, further comprisingapplying at least one oxidizing agent to the keratin fibers.
 43. Amulticompartment device comprising at least one first compartmentcomprising a dye composition comprising at least one fluorescent entitychosen from formulae (I) and (II)

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates thereof; wherein:

which may be identical or different, represent a saturated orunsaturated heterocyclic group; R_(g), R′_(g), R″_(g), R′″_(g), R_(h),R′_(h), R″_(h) and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C₁-C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom identical to ordifferent from that of the nitrogen atom; R_(i), R′_(i), R′″_(i), andR″″_(i), which may be identical or different, represent a hydrogen atomor a (C₁-C₄) alkyl group; R₁, R′₁, R₂, R′₂, R₃, R′₃, R₄ and R′₄, whichmay be identical or different, represent a hydrogen atom or a(C₁-C₄)alkyl, (C₁-C₄)alkoxy, hydroxyl, cyano, carboxyl, amino,(C₁-C₄)alkylamino or (C₁-C₄) dialkylamino group, it being possible forsaid alkyl radicals to form, with the nitrogen atom which bears them, aheterocycle comprising from 5 to 7 members, optionally comprisinganother heteroatom which may or may not be different from nitrogen;T_(a) and T_(b), which may be identical or different, represent: a σcovalent bond; at least one radical chosen from —SO₂—, —O—, —S—, —N(R)—,—N⁺(R)(R^(o))— and —C(O)—, wherein R and R^(o), which may be identicalor different, represent a hydrogen atom, a C₁-C₄ alkyl radical, a C₁-C₄hydroxyalkyl radical or an aryl(C₁-C₄)alkyl; or at least one cationic ornoncationic, heterocycloalkyl or heteroaryl radical; m, m′, n and n′,which may be identical or different, represent an integer ranging from 0to 6, wherein m+n and m′+n′, which may be identical or different,represent an integer ranging from 1 to 10; M′ represents an anioniccounterion; and Y represents: i) a hydrogen atom; ii) an alkali metal;iii) an alkaline earth metal; iv) an ammonium group:N⁺R^(α)R^(β)R^(γ)R^(δ) or a phosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ)with R^(α), R^(β), R^(γ) and R^(δ), which may be identical or different,representing a hydrogen atom or a (C₁-C₄)alkyl group; or v) athiol-function-protecting group; it being understood that when the atleast one entity chosen from those of formulae (I) and (II) containsother cationic parts, it is associated with at least one anioniccounterion allowing the at least one entity chosen from those offormulae (I) and (II) to achieve electroneutrality; and at least onesecond compartment comprising at least one reducing agent.
 44. Themulticompartment device according to the claim 43, further comprising aleast one third compartment comprising at least one oxidizing agent. 45.A process for lightening dark keratin fibers comprising, applying todark keratin fibers at least one fluorescent entity chosen from formulae(I) and (II)

the organic and mineral acid salts, optical isomers and geometricalisomers, and the solvates hereof; wherein:

which may be identical or different, represent a saturated orunsaturated heterocyclic group; R_(g), R′_(g), R″_(g), R′″_(g), R_(h),R′_(h), R″_(h) and R′″_(h), which may be identical or different,represent a hydrogen or halogen atom, an amino, (di)(C₁-C₄)alkylamino,cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C₁-C₄ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, (C_(i)C₄)alkylcarbonyloxy,(C₁-C₄)alkoxycarbonyl, (C₁-C₄)alkylcarbonylamino, acylamino, carbamoylor (C₁-C₄)alkylsulphonylamino group, an aminosulphonyl radical, or a(C₁-C₁₆)alkyl radical optionally substituted with a group chosen from(C₁-C₁₂)alkoxy, hydroxyl, cyano, carboxyl, amino and(di)(C₁-C₄)alkylamino, or else the two alkyl radicals borne by thenitrogen atom of the amino group form a heterocycle comprising from 5 to7 members and optionally comprising another heteroatom identical to ordifferent from that of the nitrogen atom; R_(i), R′_(i), R′″_(i), andR″″_(i), which may be identical or different, represent a hydrogen atomor a (C₁-C₄) alkyl group; R₁, R′₁, R₂, R′₂, R₃, R′₃, R₄ and R′₄, whichmay be identical or different, represent a hydrogen atom or a(C₁-C₄)alkyl, (C₁-C₄)alkoxy, hydroxyl, cyano, carboxyl, amino,(C₁-C₄)alkylamino or (C₁-C₄) dialkylamino group, it being possible forsaid alkyl radicals to form, with the nitrogen atom which bears them, aheterocycle comprising from 5 to 7 members, optionally comprisinganother heteroatom which may or may not be different from nitrogen;T_(a) and T_(b), which may be identical or different, represent: a σcovalent bond; at least one radical chosen from —SO₂—, —O—, —S—, —N(R)—,—N⁺(R)(R^(o))— and —C(O)—, wherein R and R^(o), which may be identicalor different, represent a hydrogen atom, a C₁-C₄ alkyl radical, a C₁-C₄hydroxyalkyl radical or an aryl(C₁-C₄)alkyl; or at least one cationic ornoncationic, heterocycloalkyl or heteroaryl radical; m, m′, n and n′,which may be identical or different, represent an integer ranging from 0to 6, wherein m+n and m′+n′, which may be identical or different,represent an integer ranging from 1 to 10; M′ represents an anioniccounterion; and Y represents: i) a hydrogen atom; ii) an alkali metal;iii) an alkaline earth metal; iv) an ammonium group:N⁺R^(α)R^(β)R^(γ)R^(δ) or a phosphonium group: P⁺R^(α)R^(β)R^(γ)R^(δ)with R^(α), R^(β), R^(γ) and R^(δ), which may be identical or different,representing a hydrogen atom or a (C₁-C₄)alkyl group; or v) athiol-function-protecting group; it being understood that when the atleast one entity chosen from those of formulae (I) and (II) containsother cationic parts, it is associated with at least one anioniccounterion allowing the at least one entity chosen from those offormulae (I) and (II) to achieve electroneutrality, and optionallyapplying at least one reducing agent.